The present invention relates to a cleaning device for use in an image recorder.
In an electrophotographic copier, facsimile apparatus or similar image recorder, a cleaning device is disposed in close proximity to an image carrier in the form of a drum so as to remove a toner which remains on the drum after image transfer. The cleaning device includes a cleaning blade which is pressed against the drum by a solenoid or similar urging means. Assuming that the surface of the drum is constituted by a selenium layer or a combination of selenium and tellurium layers, it remains relatively hard so long as the temperature of the drum is of a usual level. In this condition, leaving the cleaning blade in pressing contact with the drum surface is not critical. However, the temperature of the drum often rises by 15 degrees or so when the ambient temperature is high or when the drum is operated nearly continuously. When the cleaning blade is held in pressing contact with the surface of the drum while the drum temperature is as high as above 40 degrees, for example, the surface of the drum becoms soft to allow the edge of the cleaning blade to bite thereinto resulting in a linear concavity or trace being produced in and along the axis of the drum. This concavity in the drum surface appears on a reproduction as a black line. In addition, the edge of the cleaning blade drops in such a concavity while the image recorder is operated, producing noise. Especially, in a wet-process electrophotographic copier which uses a liquid developer, a toner firmly adhere to the drum surface so that a greater cleaning force than with a dry-process electrophotographic copier is required which would cause the cleaning blade to bite deeper into the drum surface.
In the light of this, it has been customary with an electrophotographic copier, for example, to deenergize the solenoid and thereby release the cleaning blade from the drum surface upon the lapse of a certain period of time (usually 15 minutes) after a copying operation. This, however, causes the cleaning blade to be brought into and out of contact with the drum surface frequently and thereby causes a substantial amount of toner to be scattered around and/or dropped from the cleaning blade to smear the interior of the copier.